As generally shown in FIG. 1, in the motion picture industry an original motion picture negative film is exposed during a camera exposure operation 10, developed into a processed camera negative 12 and subsequently processed in one of several ways. In the motion picture industry, there are two common subsequent processes: an optical printing process 18 and a film scanning process 20. It is well known that the optical printing process may be practiced in several ways in order to optically transfer the image data to a print material. In a single stage optical process, the optical transfer is direct; that is, the color negative film 12 is optically printed onto another photosensitive material, e.g., a release print material 22 such as Eastman Color Print Film 5386™, to produce a color positive image suitable for projection. To avoid harming the original negative in the subsequent processes, the camera negative 12 may be converted into an interpositive 14, which is a positive image optically produced on a negative copying material with the same contrast and the same extended range of the scene as the camera negative. (Either element 12 or 14 then constitutes the photographic film element 16 identified in FIG. 1, which is subsequently processed.) In such a multi-stage process, the optical transfer of the original image data to a print material is indirect; that is, the interpositive 14 is used to optically produce numerous duplicate negatives 24, which are then optically printed (process 26) onto release prints 28, which may also be Eastman Color Print Film 5386™.
In the other subsequent process in the motion picture industry, the color negative film information (camera negative 12) or the color print film information (interpositive 14) is transferred into a video signal using a telecine transfer device in the telecine scanning process 20. (As with the optical scanning process, the interpositive is a negative copying material that is used to produce a positive with the same contrast as the original negative and the same extended range of the scene; this element is then used in the trade as the element to scan on the telecine device without risking harm to the original negative.) Various types of telecine transfer devices are described in Engineering Handbook, E. O. Fritts, Ed., 8th edition, National Association of Broadcasters, 1992, Chapter 5.8, pp. 933–946 , the disclosure of which is incorporated by reference. The most popular of such devices generally employ either a flying spot scanner using photomultiplier tube detectors, or arrays of charged-coupled devices, also called CCD sensors. CCD sensors include either an area array scanner (captures the full frame at once) or a linear line scanner (the film is transported across a line array of sensors and the total image is then a reconstruction of all the lines to give an area image). Telecine devices scan each negative or positive film frame transforming the transmittance at each pixel of an image into a voltage. The signal processing then inverts the electrical signal in the case of a transfer made from a negative film in order to render a positive image. The signal is carefully amplified and modulated, and fed into a cathode ray tube monitor 30 to display the image, and/or recorded onto magnetic tape for storage in a recording stage 32. The output of the telecine scanning process 20 may be applied to a film recording stage 34, which produces a negative film 36 that can be optically printed out as a release print.
The monitor 30 is typically a high definition (HD) monitor with the data provided from the telecine scanning process 20 incorporating the characteristics of the monitor such that the video image is pleasing to the operator. In this use of the telecine transfer device, only a restricted range of the total image on the film element 16 is used (i.e., compressed into the tonal range of the monitor). If a video tape is desired from the video recording process 32, the data associated with the image displayed on the monitor is written to digital (or analog) tape. If digital data is required for the subsequent film writing process 34, the telecine device has an output data pathway which includes one dimensional look up tables (1D LUTs) 38 that transform a video tone scale to a more film like tone scale such that the resulting negative 36 produced will print onto a photographic print element 28 and look at least somewhat like a film system image. The video monitor image, however, usually will not match the final print image in tone scale and color reproduction.
In the previous examples from the prior art, the digital data acquired in the telecine scanning process 20 only has the restricted range of the initial video range capture. If the client desires changes to the final look, the operator can only modify the data obtained. If there was information on the photographic film element 16 outside of the range initially captured, then it is not represented in the data and cannot be used. An example of this could be an interior scene with a person sitting at a desk with an outside window in the background. In a normal telecine transfer, the very high exposure of the outside window relative to the proper lightness of the interior foreground will show up as a very light area without much detail. However, the film element has considerable detail in this area but without advanced technical techniques it cannot be displayed on the HD monitor. The extended range can be captured in a second scan through the telecine scanning process 20 with a different setup that maximizes the high exposure area. The two scans can then be merged with advanced digital techniques. One drawback of this technique is that the extended range that needs to be captured must be known at the time of the original scan, otherwise a future new scan is required with added cost. Moreover, while the desired transfer would capture the entire extended range of the negative, in the current system the HD monitor would be unable to effect correct tone scale and color reproduction and thus would be useless as a creative display device.
In the motion picture trade, some postproduction facilities use a technique that tries to capture the complete negative range. In this technique, the highest density on the negative is assigned to the highest video level and the lowest density on the negative is assigned to a low video level (usually not the full low to high range available in the bit depth of the transfer). This data can then be color corrected on another device, which inputs data and allows digital manipulation to give an image on a monitor that is pleasing to the client. In either case another device, usually another computer system, is employed in an attempt to show a film look from the data to validate the image content before committing to film recording.
In current telecine transfer practice, there is no assurance that the data will render on film (by means of a film recorder) as intended. The dynamic range on the negative is not preserved in a consistent manner. Moreover, the current telecine transfer practice of viewing the scanned video data on a HD monitor and then writing to data (and film) through a 1D LUT can produce changes in the very low tones (blacks and very dark colors) in the data that are not able to be displayed on the monitor.
For a effective film recording process, what is ultimately needed is a telecine transfer process that produces data that can be used, without operator intervention, as input to a film-recording device to produce a negative, which will result in a print that matches a print optically produced from the original negative.